Acceptable privacy systems for wireless communications systems such as cordless and cellular telephones have in common some way of authenticating a mobile unit. Once authentication occurs, the mobile unit may communicate with a base station or another mobile unit. After authentication, however, no standard or easily adaptable method or system exists to ensure that wireless communications are private or secure. The ease with which a skilled person can intercept wireless communications establishes a need for privacy in these communications. Moreover, as cellular telephones become increasingly wide-spread, the need for privacy in these communications will surpass its current high level.
To implement known privacy schemes in wireless communications requires additional circuitry that increases the purchase price of these systems. For example, U.S. Pat. No. 5,153,919 to Reeds et al. (hereinafter Reeds) describes an authentication and data encryption/decryption technique that requires both additional circuitry and additional cellular telephone systems software reprogramming. This scheme substantially increases the cellular telephone unit purchase price for systems that use it. Competitive market forces, however, continue to require that the purchase price of cellular or cordless telephones and other wireless communication systems remain as low as possible.
Any system that protects wireless communications must also be flexible to combat creative attempts to violate or render ineffective the associated privacy scheme. A problem with systems similar to that of Reeds, to the contrary, is that the authentication and encryption circuitry has a high likelihood of becoming outmoded and its utility diminishing once its operation becomes well-known. Furthermore, the combination of technology variances, jurisdictional variances, differing legal constraints on use of otherwise private information, and the various and ever changing legal tests and standards that provide privacy in electronic communications all require flexibility in any approach to making wireless communications private. Existing systems cannot respond to these differing circumstances. In fact, there does not exist a method and system that provides a flexible privacy scheme for wireless communications that is both economical to use and adaptable to existing and future wireless communications scenarios.